This invention relates to an electronic component cooling apparatus for cooling an electronic component such as an MPU or the like, and more particularly to an electronic component cooling apparatus of the type that a heat sink on which an electronic component is mounted is forcibly cooled by air fed from a fan unit.
An electronic component cooling apparatus which has a heat sink including a plurality of radiation fins arranged so as to be spaced from each other at intervals while being parallel to each other incorporated therein has been conventionally known in the art, as disclosed in U.S. Pat. Nos. 5,309,983, 5,519,574 (see FIG. 3 of the patent), U.S. Pat. No. Design 403,760, U.S. Pat. Nos. 5,494,098 and 5,835,347. The conventional electronic component cooling apparatus as shown in the above cases, is constructed so as to discharge air in both directions in which each of the radiation fins extends.
Another conventional electronic component cooling apparatus is disclosed in U.S. Pat. No. 5,740,014, which is so constructed that a plurality of parting slits are formed so as to be perpendicular to all of radiation fins arranged on a base of a heat sink in a manner to be parallel to each other, to thereby divide the radiation fins into fine plate-like strips. Then, air is blown against the strips from an axial fan to increase cooling efficiency of the electronic component cooling apparatus. Also, in the electronic component cooling apparatus, the radiation fins arranged in parallel to each other are entirely or substantially entirely contacted at an end thereof with a top plate of a fan unit mounting frame for mounting a fan unit thereon.
A further conventional electronic component cooling apparatus is disclosed in U.S. Pat. Nos. 5,615,998 and Des. 403,760. The cooling apparatus disclosed includes an engagement structure which permits a plurality of engaging sections provided on a casing of a fan unit and a plurality of engaged sections provided on a heat sink to be engaged with each other by merely approaching the casing of the fan unit to the heat sink when the fan unit is mounted on the heat sink.
Still another conventional electronic component cooling apparatus is proposed as disclosed in Japanese Patent Application Laid-Open Publication No. 284116/1999. The cooling apparatus disclosed is so constructed that an end of each of plural radiation fins and a top plate of a fan unit mounting frame for mounting a fan unit thereon are arranged so as to be spaced from each other at a predetermined interval to define an air flow space therebetween.
Currently, an electronic equipment such as a CPU or the like generally tends to generate more heat than before, and it is highly required to enhance cooling performance of an electronic component cooling apparatus. To this end, it is proposed that radiation fins each are made of a copper plate relatively reduced in thickness which exhibits enhanced thermal conductivity. However, when the radiation fins are arranged so as to provide an interval between the radiation fins and a top plate of a fan unit mounting frame for mounting a fan unit thereon while being reduced in thickness, the radiation fins fail to be positively used as a support for the frame. This is solved by rendering a mechanical structure of the fan mounting frame rigid. However, an increase in rigidity of the mechanical structure of the fan mounting frame leads to an increase in manufacturing cost of the frame, leading to a failure in demand for cost reduction.
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide an electronic component cooling apparatus which is capable of firmly fixing a fan unit mounting frame to a heat sink, when radiation fins of the heat sink are not intended to be positively used as a support for the fan unit mounting frame.
It is another object of the present invention to provide an electronic component cooling apparatus which is capable of firmly fixing a fan unit mounting frame to a heat sink without increasing mechanical strength of the fan unit mounting frame.
It is a further object of the present invention to provide an electronic component cooling apparatus which is capable of changing a cooling performance thereof depending on a variation in temperature.
It is still another object of the present invention to provide an electronic component cooling apparatus which is capable of exhibiting enhanced heat dissipating performance as compared with heretofore.
It is yet another object of the present invention to provide an electronic component cooling apparatus which is capable of facilitating position ing between a fan unit mounting frame and a heat sink and ensuring firm engagement therebetween, not permitting the engagement to come off easily.
In accordance with the present invention, an electronic component cooling apparatus is provided. The electronic component cooling apparatus includes a heat sink, a fan unit and a fan unit mounting frame made of a synthetic resin material for mounting the fan unit on the heat sink. The heat sink includes a radiation fin unit including a plurality of radiation fins made of a material increased in thermal conductivity, as well as a base made of a material increased in thermal conductivity. The base is mounted on a front surface thereof with the radiation fin unit and on a rear surface thereof with an electronic component to be cooled. The radiation fins are arranged so as to extend in a first direction perpendicular to the front surface of the base and in a second direction perpendicular to the first direction and along the front surface of the base. The radiation fins are arranged so as to be spaced from each other at predetermined intervals in a third direction perpendicular to the first and second directions. The radiation fins each are fixed, to the base, at an end thereof positioned on one side in the first direction. The base is formed with a hook engagement at each of a pair of edges thereof positioned on both sides in the third direction.
The fan unit incorporated in the electronic component cooling apparatus feeds air for cooling the radiation fin unit. The fan unit includes an impeller including a plurality of blades and rotated by a motor and is arranged on the other side in the first direction mentioned above with respect to the radiation fin unit. The fan unit mounting frame for mounting the fan unit on the heat sink includes a top plate for supporting the fan unit thereon, a pair of side plates and at least a pair of mounting legs. The top plate is arranged outside the radiation fin unit so as to define a gap sufficient to provide an air flow space continuously extending on both sides in the second and third directions between the top plate and an end of each of the radiation fins positioned on the other side in the first direction. The top plate is provided with an air guide hole for guiding air sucked by the fan unit to the air flow space. The side plates are arranged so as to extend, toward the base, from a pair of ends of the top plate positioned on both sides in the third direction. The mounting legs each are connected at one end thereof to each of the side plates and provided at the other end thereof with a hook engaged with each of the hook engagements. The side plates and mounting legs are formed into a shape and dimensions which keep the side plates and mounting legs from fully covering side surfaces of the radiation fan unit positioned on both sides in the third direction.
The fan unit mounting frame includes a first pivotal movement preventing engagement structure which is engaged with the radiation fin unit to prevent the top plate from pivotally moving in the third direction and a second pivotal movement preventing engagement structure which is engaged with the radiation fin unit to prevent the top plate from pivotally moving in the second direction.
The above-described construction of the present invention permits air for cooling discharged from the fan unit to flow through the air flow space defined between the radiation fin unit and the top plate, gaps defined between the radiation fins and gaps defined between the side plates and outermost two of the radiation fins of the radiation fin unit, to thereby efficiently cool the radiation fins. In particular, the present invention is so constructed that air flowing through the air flow space is directly fed to the gaps between the respective adjacent two of the radiation fins of the radiation fin unit. This permits air of low temperature or cold air to be rapidly fed from the fan unit to the radiation fins arranged apart from the fan unit, to thereby significantly enhance cooling efficiency of the electronic component cooling apparatus.
In particular, in the electronic component cooling apparatus of the present invention, the hooks arranged on the mounting legs of the fan unit mounting frame are engaged with the hook engagements arranged on the base, to thereby prevent movement of the top plate of the fan unit mounting frame in the first direction. Also, the above-described arrangement of the first pivotal movement preventing engagement structure and second pivotal movement preventing engagement structure effectively prevents the top plate from moving in the second and third directions, so that the fan unit mounting frame may be firmly mounted, with increased resistance to deformation, on the heat sink without substantially increasing mechanical strength of the fan unit mounting frame.
Thus, the present invention ensures firm mounting of the fan unit mounting frame on the heat sink even when the radiation fin unit is formed by subjecting a thin metal plate to working or machining in order to enhance heat dissipating performance thereof and therefore the mechanical strength of the radiation fan unit is reduced. Such a radiation fin unit may be made by subjecting a single metal plate having a thickness which permits bending thereof to working. Such a radiation fin unit may be constructed by connecting the radiation fins to each other in order in such a manner that, of both ends of each of the radiation fins defined on both sides in said first direction, one end of the radiation fin positioned on the one side in the first direction is connected to an end of a first adjacent radiation fin positioned on the one side in the third direction by a first connection. which end of the first adjacent radiation fin is positioned on the one side in the first direction, and the other end of the radiation fin positioned on the other side in the first direction is connected to an end of a second adjacent radiation fin positioned on the other side in the third direction by a second connection, which end of the second adjacent radiation fin is positioned on the other side in the first direction. Such construction of the radiation fin unit permits the radiation fin unit to be readily made of a single metal plate.
In other words, the radiation fin unit may be configured into a meandering shape in such a manner that the radiation fins each are connected at an end thereof positioned on one side in the first direction to an end of a first adjacent radiation fin positioned on the one side by a first connection and at an end thereof positioned on the other side in the first direction to an end of a second adjacent radiation fin positioned on the other side in the first direction by a second connection. The first connection may be joined to the front surface of the base.
The first pivotal movement preventing engagement structure may be constituted by one or more projections fitted in one or more gaps defined between adjacent two of the radiation fins in the first direction.
When each of the projections is fitted in each of the gaps, the projection acts as an anchor caught by the radiation fin adjacent thereto when force toward both sides in the third direction is applied to the fan unit mounting frame, resulting in restraining pivotal movement of the top plate in the third direction.
A casing of the fan unit and the fan unit mounting frame may be formed so as to be integral with each other. However, this causes the casing and fan unit mounting frame to be complicated in configuration, leading to an increase in manufacturing cost. Thus, the casing of the fan unit is preferably formed separately from the fan unit mounting frame. In this instance, the plural projections may be arranged on the top plate so as to form at least one projection chain along a circumference of the air guide hole. When such a projection chain is arranged, the projection chain is formed on an outside thereof with an elongated slit so as to continuously extend along the projection chain. The top plate is deflected at a portion thereof on which the projections are formed so as to project toward the other side in the first direction while keeping the fan unit mounting frame mounted on the heat sink. More specifically, the projections each are formed into a width somewhat larger than that of each of the gaps, so that the projection is forcedly fitted in the gap. This permits the portion of the top plate on which the projection chain is formed to be deflected, so that the projections may be forced against the radiation fin unit. Such arrangement cooperates with the above-described engagement between the hooks of the mounting legs and the hook engagements of the heat sink to effectively prevent the fan unit mounting frame from moving toward the other side in the first direction.
Alternatively, the present invention may be so constructed that the projection chain is arranged outside the slit and the slit is provided on an inside thereof with a protrusion abutted against ends of the radiation fins positioned on the other side in the first direction. This permits the protrusion to be forced against the ends of the radiation fins using the above-described deflection. Such construction likewise effectively prevents movement of the fan unit mounting frame toward the other side in the first direction. In this instance, the projections each may be formed into a configuration which permits the projection to be loosely fitted in the gap. Also, in this instance, the second pivotal movement preventing engagement structure may be constituted by connection bars as described below.
The second pivotal movement preventing engagement structure may be constituted by a pair of protrusions arranged so as to extend from the top plate toward the base, to thereby be abutted against a part of end surfaces of each of the radiation fins positioned on both sides in the second direction, resulting in preventing pivotal movement of the radiation fin unit in the second direction. Such construction permits the protrusions in a pair to act as a stopper with a simple structure, to thereby prevent pivotal movement of the top plate of the fan unit mounting frame in the second direction, when force in the second direction is applied to the fan unit mounting frame.
In a preferred embodiment of the present invention, a pair of elongated connection bars may be arranged so as to connect a pair of ends of the side plates positioned on both sides in the second direction thereto, respectively. This prevents a reduction in mechanical strength of the fan unit mounting frame even when the fan unit mounting frame is made of a thinner material. In this instance, the connection bars may act also as the second pivotal movement preventing engagement structure. This results in the electronic component cooling apparatus being simplified in structure. In this instance, at least one short connection bar may be arranged so as to connect the connection bars and top plate to each other. This further enhances mechanical strength of the fan unit mounting frame without substantially obstructing flow of air for cooling.
The above-described configuration of the present invention permits air for cooling discharged from the fan unit to flow through the air flow space, the gaps, and the gaps defined between the side plates and each of the legs and the side surface of the radiation fin unit positioned on each of both sides in the third direction. This attains rapid and uniform cooling of the whole radiation fin unit.
The blades of the fan unit each may be positioned at a part thereof in the air flow space. This enhances cooling efficiency of the electronic component cooling apparatus.
In a preferred embodiment of the present invention, the legs each are connected to a central portion of each of the side plates. The side plates have a pair of auxiliary support legs abutted against the edges of the base so as to be positioned on both sides of the legs in the second direction. Such construction permits each of the auxiliary support legs to act as a reinforcing member, to thereby enhance mechanical strength of the fan unit mounting apparatus. An excessive increase in size of the auxiliary support legs obstructs flow of air for cooling. Thus, in order to avoid the problem, the auxiliary support legs are preferably formed into a size as large as possible while ensuring that it does not obstruct air flow.
The fan unit may be mounted on the top plate of the fan unit mounting frame through a removable engagement structure. Also, the fan unit may include a motor, an impeller rotated by the motor, a motor drive circuit for driving the motor and a temperature sensor arranged in a manner to be incorporated in or adjacent to the motor drive circuit, wherein the motor drive circuit controls a rotational speed of the motor depending on an output of the temperature sensor. This leads to a variation in air discharged from the fan unit depending on an ambient temperature, thus resulting in enhancing the cooling performance of the cooling apparatus.